In the genealogy research world, knowing your ancestors' neighbors' business will provide clues to your own family history, so, put your good manners to the side. Go ahead and look at the neighbors' cemetery records, deeds, wills, probate records, vital records, taxes, diaries, personal letters, etc. Its okay to check out the family history of his wife or her husband. Its okay to know how they acquired those cows. Go ahead and be nosy.
One of my favorite research tools is the Civil War pension records. What do you do if you don't find a relative with pension records, as in my case? Look and see if the neighbors has one. My relatives testified in their neighbors cases and I was able to confirm oral history and relationships.
Go ahead and use your favorite research tool on the neighbors. You may be handsomely surprised at what you discover about your own people.